2008 Dragon 700 Engine Cutting Out Over 7600 RPM

[fargineyesore]

Thanks.

 

[Culvert]

Did you ever find out what the issue was?
I have an 07 D7 that when Im wide open in the deep snow it will drop to 7600Rpm & stay there untill I burp the throttle. It will then spin back up to 81-8200 Rpm for a few sec/min then drop back to 7600 untill you play with throttle.

I have tried new plugs, cleaned exhaust valves, pulled ypipe & welded a crack. Still does not run right.

07 D7, SLP pipe, HPS can, 10-62 weights, silver spring. stock helix with black/purple spring. 2200' elev
Sled has bogged like this with the 10-62 & 10-64 weights.

 

[Kranked]

I still havnt figure mine out. Recently blew my motor up so I took everything apart. Noticed one of my exhaust bellows was dryed out, it looks like water got in that little hole on top of the exhaust valve and sat on the bellow. I took my secondary clutch off for the first time and noticed there's a lot of wear in between the two sheaves. Wore half way through the washer that seperates the sheaves. There's defently some friction in there.
I don't know what was causing the low Rpms but hopefully with this new motor it runs a little better.

 

[fargineyesore]

Motor just went, piston put hole in crank case. Not sure what caused it yet, but fuel filter was dirty. I'm just going to try to find a used engine that runs then sell the machine. I've had it as this is the second motor now. First was due to bad voltage regulator. Anyone know where to look for one?

 

[Kranked]

Maybe the low Rpms is a sign that the motors about to give up?

 

[sledneck_03]

my 08 700 has 4800 miles, i run 64s at 1500 ft and it has trouble hitting 8100 all the time.

Had 58s in it at 5000 ft and it shows 8000, 8100, 8200 max. Thats to low for weight, should be running 60s (-2g for every 2000 ft)

I changed the belt, the plugs, the fuel filter. It runs strong, just wont over rev, it does bog out wide open every once in a while and kills it down to 7600 rpms, thought it was water in fuel???

sounds like i have the same problems.

I just read around on hardcore sledder, i think my issue is the det sensor.

 

[Culvert]

I just went over the whole sled again the other day & put a set of 10-64 in for a local ride at 2000'
Have new fuel filter, cleaned the valves, 130 Psi both holes, new plugs.
I have been told TPS, but why not all the time? I can rip down a trail & she pulls good at 81-8300 RPM. Hit some deep snow & try to hold her WFO & she will bog once hitting top RPM then drop to 7600 & just hang there forever if I didnt burp the throttle.

How do you test the Det sensor?

 

[hawkn]

Hey guys.
I'm having the same issues here with a 2009 Polaris 600 H.O. rmk 155"

I've been running since oct. 2012 and had a few issues since then, a few cut-off's with high ambient temp, but nothing serious like sounds or something.

First I got the resistor for running with ethanol fuel (we have 95 octane with ethanol and 98 octane fuel here in Norway, then I changed the fuel filter, no change, spark plugs, no change, checked wirings and such, but still nothing.

Did a comp test on the cylindres, they had the exact same values.

Thought it was exhaust valves so I cleaned them, the one closest to the clutch side had almost chewing gum like oil in it, the other was fine, after cleaning it was no different then before, changed spark plugs and nothing else than it felt stronger but sill not over 75-7900 rpm.
Checked the EGT sensor with my voltmeter, it seems to be open all the time, that was confirmed after running the sled and getting the check engine light flashing 5 times when driving for more than 2-300m.

When I get the sled back home I'm going to the local polaris dealer for a check with the Polaris Digital Wrench, seems to be the only option.
It seems to me that the TPS might need to be calibrated and the rest calibrated, this is because when I checked the spark plugs, one had the electrode with brown color, the other one was much brighter.

And, yes, wen running it it seems to go into some kind of DET mode, because it runs VERY rich and doesn't run past the 7500-7900 rpm area, but with DET mode, it shouldn't run over around 6k rpm ?

edit: also forgot to mention that I've clraned both clutches after the problem came di nothing with the problem :-(

 

[sledneck_03]

I just went over the whole sled again the other day & put a set of 10-64 in for a local ride at 2000'
Have new fuel filter, cleaned the valves, 130 Psi both holes, new plugs.
I have been told TPS, but why not all the time? I can rip down a trail & she pulls good at 81-8300 RPM. Hit some deep snow & try to hold her WFO & she will bog once hitting top RPM then drop to 7600 & just hang there forever if I didnt burp the throttle.

How do you test the Det sensor?

How many miles do you have cause I trouble shooted my sled today.

Mine will haul up to 8000-8100 from a stop.

You go mid throttle to wide open, 7600 and slowly goes up to 7900 some times, some times goes up to only 7850 right away.

It also out of no where if I'm playing with the throttle going mid to wide open driving it will bog down to 6600 or 7200 and some quick play in the throttle will get it up again.

I've found like you changing a bunch of motor stuff changes nothing. I was with my dad who's sledded for 30-40 years and he's like I think its your clutch.

We took the primary spring out and tilted the cover and there is alot of play. Also the spider moves alot, and when I bolted it back together with no spring and it actually is sticky about a cm from pushing all the way in, and pushed all the way in like it would be wide open it sticks there but this is only pushing slow . If you slam it one way and the other it slides smooth.

Basically we think from it being so sloppy its keeping it from revving past 8000 all the time and why some times it will get up to 8200. Also we think its binding and sticking keeping it from back shifting or shifting forward. Mine seemed like a bog before but today it was more like a manual trans that needed shifting cause it just sat at 6600 and I pushed it wide open holding it there at 6600 and the motor didnt sound like a bog more like it was loading funny.

I'm getting my clutch serviced this week. Buttons replaced or shimmed, and new bushings. My rollers and pins were in great condition.

I would do what I did, take the clutch cover off and see how loose your spider and bushings are. its possible your having the same issues I am.

My dads f8 has about 5000 miles on it too, he does not have the bogging issues we have but his will not rev over 7900 any more either. So he's thinking he needs a full clutch servicing too.

 

[Culvert]

I have a brand new clutch on it as I installed the elec starter kit for the wife couple weeks ago & it comes with brand new Pri.
It still had the bogg issue. Took it to the dealer on Fri & it had about 80 codes for voltage issues. Crank sensor, Injectors, ECU. Tested the Voltage Reg & it was fried.
New VR installed & no more issues riding at any RPM. Hits 8200 in any snow condition now.

Take yours in & have VR tested. You will burn it down very soon if the VR is bad & not sending voltage to the injectors.

 

[sledneck_03]

Ok sounds good, thanks. Mine isn't acting quite like yours so I'm going to try the primary cause mine very worn if that's not a fix ill go get it scanned.

 

[hawkn]

Today I spoke to a polaris dealer other than the local dealer.
Local dealer = burned down engine, was in for tps test/calibrating and they did not even hook it up with a cable to check.
dealer far away = the said check exhaust valves/solenoid, reeds, fuel filter, air box for leaks, voltage regulator, and conpression with WOT (I checked without touching the throttle and it showed 93 psi after 4 pulls, guessing it will be higher with WOT unless reeds are leaking?

Sent from my GT-N8000 using Tapatalk HD

 

[Sparky's]

I just had the same kind of problem on my 08 700. I was only hitting 78-7700 rpm when it could hit 8200. Took mine in and the primar clutch was totally screwed!!! Brand new clutch fixed the problems. I couldn't see the worn parts or the broken spring. I was beating my head to figure it out so I just took it to the dealer. They had it figured out in no time

 

[Culvert]

Ya but the OP problem is the sled hits 81-8200 RPM then falls on its face to 7600 & hangs there untill you burp the throttle. I had a brand new primary on & it would hit 8100 RPM then falls to 7600 when motor is loaded. Burp throttle back to 8100 for a few secs, mins then falls again.

New VR & no more issues at all in any riding conditions.

 

[hawkn]

Seems like in my case the gas on the local pump has ethanol, have the ethanol resistor though.
But also it seems to be lower comp on both cylindres,93 psi, and seizures on the intake side of the cyls and pistons.
Hopefully the crankshaft and bearings are ok.....

Will post updates when I've teared down the engine, or found the problem.

edit:
Checked with a new comp. gauge....its just under 120 psi.
Video made for showing bogging issue -->
Video also available on youtube --> http://youtu.be/vM0UmlUxCsA

Btw. is it possible that the cause of this is high fuel pressure ? I just saw in the service manual it says Fuel Pressure - PSI (bar) 58-60 (4.0-4.1) and I have 4.5 bar at idle.?


Sent from something.....of another world..

 

[hawkn]

Seems like in my case the gas on the local pump has ethanol, have the ethanol resistor though.
But also it seems to be lower comp on both cylindres,93 psi, and seizures on the intake side of the cyls and pistons.
Hopefully the crankshaft and bearings are ok.....

Will post updates when I've teared down the engine, or found the problem.

edit:
Checked with a new comp. gauge....its just under 120 psi.
Video made for showing bogging issue -->
Video also available on youtube --> http://youtu.be/vM0UmlUxCsA

Btw. is it possible that the cause of this is high fuel pressure ? I just saw in the service manual it says Fuel Pressure - PSI (bar) 58-60 (4.0-4.1) and I have 4.5 bar at idle.?


Sent from something.....of another world..

So, Polaris dealer a few hours away diagnosed the problem and fixed the problem with the sled for 10% of the cost estimated by the local dealer.
Swapped EGT, new sealing ring between exhaust manifoil and exhaust pipe, adjusted TPS from 0,93 to 0,95 volts, also checked and adjusted the position of the throttle bodies.
Now the sled runs great and no more worries.
Local dealer claimes burned down cyls and pistons without comp test (wich came up to around 120 psi with a working gauge at the dealer a few hours away)

Sent from something.....of another world..

 

[Sparky's]

Changing out the exhaust bellows maybe the thing to do

 

[Trashy]

Changing out the exhaust bellows maybe the thing to do

Rhodesie ( a friend here) once told me about a RMK in his shop, that the bellows were starting to let go. It would idle fine, and decent mid. But when it went to WOT, the exhaust would push one side of the bellows down, and restrict the exhaust from leaving.

 

[Sparky's]

That's what mine was doing. Now it's back to be normal, stopped revving at 7600 tops